Composition for adhering plastic film to a vapor penetrable non-metallic substrate

ABSTRACT

This invention relates to an adhesive composition for applying a plastic film of a vapor penetrable backing or core material comprising an aqueous emulsion of an aliphatic 1-olefin and a vinyl ester of a lower monocarboxylic acid, the proportions of olefin in the copolymer being from 5-25 parts by weight the proportion of vinyl ester being the necessary remainder to make 100 parts total weight of copolymer and a water dispersible nonseparating combination of (1) a water soluble ester of a monoC1-C4 alkyl ether of a C2-C8 glycol with a C2-C4 saturated monocarboxylic aliphatic acid and (2) a plasticizing ester of glycerin with saturated C2-C4 monocarboxylic aliphatic acid, the ester of the said ether and the plasticizing ester being dispersed in substantially non-separating condition in the aqueous phase of the emulsion.

United States Patent 1 51 3,668,1 5 8 Keithley 1 *June 6, 1972COMPOSITION FOR ADHERING 3,423,353 l/l969 Levine et al. ..260/29.6 MEPLASTIC FILM o A VAPOR 3,440,199 4/1969 Lindemann et al. ..260/29.6 ME3,524,828 8/1970 Keithley ..260/l7 R PENETRABLE NON-METALLIC SUBSTRATEAppl. No.: 43,243

U.S. Cl ..260/17 R, 260/17.4 ST, 260/29.6 ME, 260/29.6 TA, 260/3l.4 R,260/3l.6 Int. Cl. ..C08b 21/32, C08b 21/34 Field of Search .....260/l7R, 29.6 ME, 29.6 TA,

References Cited UNITED STATES PATENTS Worrall et al. ..260/29.6 WA

Primary Examiner-William H. Short Assistant Examiner L. M. PhynesAttorney-George P. Maskas and Edward L. Mandell [5 7] ABSTRACT Thisinvention relates to an adhesive composition for applying a plastic filmof a vapor penetrable backing or core material comprising an aqueousemulsion of an aliphatic l-olefin and a vinyl ester of a lowermonocarboxylic acid, the proportions of olefin in the copolymer beingfrom 5-25 parts by weight the proportion of vinyl ester being thenecessary remainder to make 100 parts total weight of copolymer and awater dispersible non-separating combination of l) a water soluble esterof a mono- C,C alkyl ether of a C C glycol with a C -C saturatedmonocarboxylic aliphatic acid and (2) a plasticizing ester of glycerinwith saturated C monocarboxylic aliphatic acid, the ester of the saidether and the plasticizing ester being dispersed in substantiallynon-separating condition in the aqueous phase of the emulsion.

1 1 Claims, No Drawings COMPOSITION FOR ADHERING PLASTIC FILM TO A VAPORPENETRABLE N ON-METALLIC SUBSTRA'I'E DESCRIPTION The invention isparticularly useful in the application of a vinyl chloride and otherplastic films or sheets to a penetrable substrate, e.g., wood,cardboard, fiber board, particle or flake board, paper and woven andknitted fabrics.

in making such products, it is customary to ply the plastic sheeting,with an adhesive coating thereon, to the surface of the core or backingmaterial and then send the assembly through the nip between severalpairs of rotated, compressing rollers in series arrangement. To obtainproper adherence of the plastic sheeting to said material during theshort time during which pressure is applied has been a problem.

The present invention provides adhesive compositions which developproper tackiness and bond strength before the adhesive film iscompletely or even largely dried and solve the problem.

The invention comprises the herein described adhesive in the form of anaqueous emulsion including a resin copolymer component which comprisesan aliphatic l-olefin and a vinyl ester of a monocarboxylic acid, aspecial coalescing agent and a plasticizer combination, and suitablyalso a thickener.

The resin copolymer comprises an aliphatic l-olefin and a vinyl ester ofa low monocarboxylic acid. The aliphatic l-olefin has from two to fivecarbons and is preferably ethylene. The vinyl ester component is derivedfrom a monocarboxylic acid having from one to seven carbons such asvinyl acetate, vinyl propionate, vinyl formate and the like. Theproportions of olefin in the copolymer can be from about5-25 parts byweight, the proportion of vinyl ester being the necessary remainder,i.e., 75-95 parts by weight to make 100 parts total weight of copolymer.Preferably the proportion of olefin is from -18 parts by weight. Thepreferred copolymer is ethylene-vinyl acetate. This copolymer is wellknown to the art and is commercially available from several sources. Onesuch commercial product which is particularly preferred is Aircoflex 400made by the Air Reduction Company.

The methods for preparing the aliphatic-olefin-vinyl ester copolymers isknown and exemplified in US. patent Nos. 2,983,696; 2,703,794; 2,414,311and in copending patent application Ser. No. 874,410 filed Nov. 5, 1969,entitled, Preparation of Ethylene/Vinyl Acetate copolymers.

In addition to the named monomers used to make the vinylacetate-ethylene copolymers of this invention, small amounts up to about10 percent and suitably up to about 3 percent of a functional reactivecomonomer can be included. Such comonomers may provide polar groups toassist adhesion of the vinyl acetate ethylene copolymer to the substrateto which it will eventually be applied or they may have the function ofproviding means for cross-linking and thus contribute to strengtheningand making more resistant the adhesive bond. Such coreactive functionalmonomers can include carboxy compounds such as acrylic acid, methacrylicacid, itaconic acid, aconitic acid, maleic acid, fumaric acid, and thedimer of methacrylic acid. In the case of polycarboxylic monomers thelow alkyl monoesters of these acids are also suitable such asmono-methyl maleate, mono-ethyl fumarate, and mono-butyl itaconate.Functional reactive monomers can also be chosen from the vinyl esters ofpolybasic acids such as divinyl adipate, divinyl succinate, and divinylitaconate; from allyl esters of polyfunctional acids such as diallylfumarate, triallyl cyanurate, and diallyl vinyl citrate; otherfunctional comonomers are divinyl ether and diallyl ether. Postreactivetypes of crosslinking comonomers include glycidyl compounds such asglycidyl acrylate, glycidyl methacrylate, glycidyl vinyl ether, andglycidyl allyl ether; also N-alkylol compounds such as N-methylolacrylamide, N-methylol methacrylamide, and N- ethylolacrylamide.

Satisfactory coalescing agents are the appreciably or freely watersoluble esters or mixed esters of mono-C 1, alkyl ethers of any glycolhaving two to eight carbon atoms to the molecule, examples being themethyl, ethyl, propyl and butyl ethers of ethylene, propylene, butyleneglycols and dior other polyglycols thereof, esterified with a Caliphatic saturated acid, namely, acetic, propionic and butyric, ormixtures of said esters, the glycol ether and acid being so selectedfrom the groups stated as to make an ester having substantiallysolubility in water; an example is the acetate of the monobutyl ether ofethylene glycol (Butyl Cellosolve" acetate).

As the plasticizer which, in combination with the glycol ether ester ofkind described, promotes the desired grabbing or development oftackiness and strength before the aqueous coating film of the emulsionof the adhesive is completely dried, glycerine triacetate (triacetin)and the tributyrate (tributyrin) illustrate the class that gives thedesired results. For some purposes I may use also the monodiand tri- Caliphatic acid esters of glycerin e.g., monoand diacetin, mono-, di-, ortripropionate or butyrate esters of glycerin. The lower members of theseries give better overall results. Triacetin and tributyrin,illustrating a suitable range of solubility of the plasticizer, dissolveto the extent of about 7 parts and 0.02 parts respectively, in parts ofwater at 20 C. They are infinitely soluble in dry coalescing agents ofkind described herein.

In general, I select a combination of coalescing agent and plasticizer,from the groups given, as tested by stirring in water alone, so that thecombination is water dispersible to an emulsion that is non-separating.There is thus prevented separation of these active solvents for theresin, either by settling or rising of them in the applied adhesivefilm, either of which, if occ urring, would cause layering out of saidsolvents in excessive concentration on a face of the film, in contactwith one of the surfaces to be adhered and thus weaken the adhesivestrength at the critical zone of adhesion.

Thickeners which are satisfactory for the present purpose also are waterdispersible, examples being alkyl and hydroxyalkyl celluloses such asNatrosol 250 H" (hydroxyethyl cellulose), hydroxymethyl cellulose, ethylhydroxyethyl cellulose, the sodium salt of carboxymethyl cellulose, andthe homopolymer of ethylene oxide (polyethylene oxide) of molecularweight 4,000 to 4,000,000, such as Polyox WSR" 35, 205, or 301.Polysacchoride gums (Cf. Kirk & Othmer, Encyclopedia of ChemicalTechnology, Vol. 1 1, page 6, 1953) may be used as thickeners, forinstance, karaya, locust bean, tragacanth, or guar gum. The thickenerused is of kind and in amount to provide suitable rheological propertiesfor application of the adhesive to the substrate.

Proportions of the several components on the dry basis that arepermissible and others that are recommended in commercial adhesiveformulations are shown in the following table.

Parts by Weight for 100 Parts Co-polymer of Aliphatic l- Olefin-VinylEster The viscosity range stated in the table above is for an em ulsionof 50 percent solids, i.e., non-water materials. The viscosity for agiven set of proportions will vary in expected manner with concentrationof the solids.

The proportion of the thickener to give the viscosities varies with thethickener selected. For the preferred viscosity of 20-40 poises, theamount of Polyox when used is suitably about 0.005 1 percent of theweight of the emulsion, the

occur disappears or until uniformity results. Then I stir in thethickener which, before its admixture, is suitably either swollen inwater or mixed with a portion of said coalescing agent and then withwater. Alternatively, the thickener may be slurried in the mixed agentand plasticizer and the slurry then mixed into the latex.

The invention will be further described in connection with the followingspecific examples or the practice of it, proportions here and elsewhereherein being expressed as parts by weight unless specifically stated tothe contrary.

EXAMPLE 1 Formula A:

Component Parts by Weight (Dry) Copolymer A (vinyl acetate 80% andethylene 20%, 55% emulsion) 100 Triacetin l Methyl Cellosolve acetate(CH -C I-I OOCCI-I Natrosol 250 H 1 0.75

A part of the triacetin and the Methyl Cellosolve acetate were premixedand slowly added to the stirred copolymer latex. The resulting blend wasstirred until the initial thickening resulting from the addition of theplasticizer-coalescing agent blend had disappeared and the mix hadbecome smooth. Next introduced was the required amount of Natrosol 250 Hwhich had been previously wet with an equal weight of Methyl Cellosolveacetate, i.e., with the remainder thereof, and then dissolved insufficient water to yield a solution of 3 percent nature of thesubstrate. The product was non-staining.

The following controls B and C are not part of the invention. They showfailure of l) the coalescing agent with an insoluble plasticizer and (2)a soluble plasticizer with no coalescing agent for the present purpose.

Control B: Dry Weight Copolymer A ofFormula A 100 Dioctyl adipate l0Methyl Cellosolve acetate 5 Natrosol 250 H, 3% solution 0.75

To replace triacetin The compounding was effected with the same mixingprocedure as given for Formula A above. The product failed to show grabon any substrate until after 90 seconds drying. Because of theemulsifying power and the emulsifier in the latex of copolymer A and itsmilkiness, it is not to be expected that any visible separation of theadipate plasticizer would appear. It is considered, however, that lackof the balance of hydrophylic and lipophylic properties required in theagentplasticizer combination, for the quick grab of the adhesive, is afactor in the failure.

Control C: Dry Weight Copolymer A of Formula A [00 Triacetin Ethanol,957d 0 Although Control C also was prepared with the mixing procedureemployed for Fomiula A, the resulting products showed no grab untilafter 90 seconds. EXAMPLE 2 The procedure and composition outlined underExample 1, Formula A, were used except that the triacetin therein usedwas replaced by tributyrin. Also, the Methyl Cellosolve acetate usedtherein was replaced, separately and in turn, by equal amounts of ButylCellosolve acetate, and Butyl Carbitol acetate (acetate of butyl etherof diethylene glycol).

- In a modification of this example, the triacetin of Formula A isreplaced by an equal weight of a mixture of 50 percent triacetin and 50percent tributyrin.

EXAMPLE 3 The procedure and composition of Example 1, Formula A are usedexcept that the Natrosol thickener was replaced, separately and in turn,by 0.1 part of Polyox WSR-35 (average M.W. about 200,000) 0.5 part oflocust bean gum, 0.5 part of tragacanth and 0.5 part of guar gum, themixing and other operations being otherwise exactly as described inExample 1.

The properties of the products of Examples 2 4 are satisfactory.

EXAMPLE 4 The adhesive of Example 1, Formula A was applied by reverseroll coater to the underside of a vinyl chloride sheet to a depth. wetof about 2 mils in thickness and the thus adhesively coated sheetimmediately plied to the surface of sized, compressed paper board. Theassembly was then passed through a series of rollers adjusted to apressure of approximately 20 psi. at the nip, at a speed of about 25feet per minute. Total time in the nip was of the order of l-2 seconds.Within about 60 seconds, strength of adhesive had developed, as shownhere by the bond of the adhesive being sufficient to cause fiber tear inthe substrate under forced delamination from the vinyl chloride sheet.

EXAMPLE 5 This example provides an adhesive for application torelatively less porous substrates, such as plywood, poplar sheeting orhighly compressed wood-fiber board. In order to obtain good'bondstrength and adhesive penetration on such substrates, it is necessary toreduce the solids of the adhesive emulsion to approximately 48 to 50percent. If this solids reduction is done with additional water, aretardation of grab" results, with the time of grab being ordinarilyincreased to about 70-120 seconds or more, the exact time depending onfilm thickness and porosity of the substrate. If, however,

the solids reduction is accomplished in part with an organic liquiddiluent such as benzene, tetrahydro-furane, or a chlorinatedhydrocarbon, e.g., methylene chloride, all of evaporation rate abovethat of water, very little slowing of grab occurs, grab times of 30-50seconds duration persisting. Yet the property of penetrating thesubstrate and developing adequate bond strength remains.

An example of a formulation for such purpose is:

Parts, Dry Basis Triacetin l Methyl Cellosolve Acetate Natrosol 250 H0.7 Tributyl stannic oxide 0.5 Benzene (diluent) 13.5

The amount of diluent used to replace the water of dilution may varywithin the range about 5 15 parts for 100 parts of said copolymer.Lesser amounts are ineffectual and larger amounts defeat the purpose, byreversing the speed up .of grab, to an actual slowing down thereof.

it will be understood that it is intended to cover all changes andmodifications of the examples of the invention herein chosen for thepurpose of illustration which do not constitute departures from thespirit and scope of the invention.

What is claimed is: 1. An adhesive emulsion comprising A. water, B. aresin component containing copolymerized therein an aliphatic l-olefinhaving from two to five carbons and a vinyl ester of a lowermonocarboxylic acid having one to seven carbons, the proportion ofolefin in said resin component being from five to 25 parts by weight,the proportion of vinyl ester being the necessary remainder to make 100parts total weight of said resin component and C. a water dispersiblenon-separating combination of 1. a water-soluble coalescing agentselected from the esters of mono- C alkyl esters of C glycols with Csaturated monocarboxylic aliphatic acids and 2. a plasticizing ester ofglycerin with a saturated C monocarboxylic aliphatic acid, saidcoalescing agent and plasticizing ester being dispersed in substantiallynon-separating condition in the aqueous phase of the emulsion.

2. The adhesive emulsion of claim 1, the proportions by weight beingabout 3-15 parts of the coalescing agent and 2-15 parts of theplasticizing ester for 100 parts of said resin component.

3. The adhesive emulsion of claim 1, including an admixed thickener inthe amount to raise the viscosity of the emulsion to about 100 poises at20 C.

4. The adhesive emulsion of claim 1, including an admixed thickenerselected from the group consisting of the water dispersible alkyl andhydroxyalkyl celluloses, sodium salt of carboxymethyl cellulose,polysaccharide gums, and polyoxyethylene of molecular weight within therange 4,000 to 4,000,000, the proportion of the thickener being thatgiving to the emulsion a viscosity of about 10 -l00 poises at 20 C. whenthe proportion of water in the emulsion is approximately 40 percent ofthe total weight thereof.

5. In the emulsion of claim 4, said thickener being hydroxyethylcellulose.

6. An adhesive emulsion consisting essentially of the followingcomponents in proportion by weight approximately as follows: 70-1 10parts of water, parts of a copolymer of vinyl acetate and ethylene, theproportions by weight of the monomers copolymerized in 100 parts byweight of said copolymer being 75-95 parts vinyl acetate andcorrespondingly 5-25 parts of ethylene, 3-15 parts of the acetate of themonobutyl ether of ethylene glycol, 2-15 parts of tributyrin, and 0005-2parts of hydroxyethyl cellulose.

7. The adhesive emulsion of claim 4, said thickener beingpolyoxyethylene of average molecular weight about 200,000.

8. The adhesive emulsion of claim 3, said thickener being guar gum.

9. The adhesive emulsion of claim 1, including an admixed organic liquiddiluent, the diluent being of evaporation rate above that of water andin the proportion of about 5-15 parts by weight for 100 parts of saidcopolymer.

10. The adhesive emulsion of claim 1, wherein the resin component isethylene-vinyl acetate, ethylene being present in an amount of from lO-]8 parts by weight, the amount of vinyl acetate being the necessaryremainder to make 100 parts total weight of copolymer.

1 1. An adhesive emulsion comprising A. water, B. a resin componentcontaining polymerized therein i. an aliphatic l-olefin having from twoto five carbons,

ii. a vinyl ester of a lower monocarboxylic acid having from one toseven carbons, and

iii. a functionally reactive comonomer, selected from the groupconsisting of acrylic acid, methacrylic acid, itaconic acid, aconiticacid, maleic acid, fumaric acid, methacrylic acid dimer, the monoestersof maleic, fumaric and itaconic acids with C C alkanols, divinyladipate, divinyl succinate, divinyl itaconate, diallyl fumarate,triallyl cyanurate, diallyl vinyl citrate, glycidyl acrylate, glycidylmethacrylate, glycidyl vinyl ether, glycidyl allyl ether,N-methylolacrylamide, N-methylolmethacrylamide and N-ethylolacrylamide,the proportion of olefin in the resin component being from 5-25 parts byweight, the proportion of functionally reactive comonomer being from3-10 parts by weight and the proportion of vinyl ester being thenecessary remainder to make 100 parts total weight of resin component,

C. A water dispersible non-separating combination of i. a water-solublecoalescing agent selected from the esters of mono-C alkyl ethers of Cglycols with C saturated monocarboxylic aliphatic acids and aplasticizing ester of glycerin with a saturated C monocarboxylicaliphatic acid, said coalescing agent and plasticizing ester beingdispersed in substantially non-separating condition in the aqueous phaseof the emulsion and being in weight proportion corresponding to about3-15 parts of coalescing agent and 2-15 parts of plasticizing esters for100 parts of said resin component.

31 33 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3i 668 15 Dated June 6' 97 I g) Robert James Keithley It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

. I Y In Column 2, line 63 5", should be changed to 100--.

In Column 4, 'lines 11-12 --Ethano1, 95% (Several grades usedseparately) should start at the margin.-

Signed and sealed this 2mm day of October 1972.

(SEAL) Attest:

EDI- !ARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attestlng OfficerCommissioner of Patents

2. a plasticizing ester of glycerin with a saturated C2-4 monocarboxylicaliphatic acid, said coalescing agent and plasticizing ester beingdispersed in substantially non-separating condition in the aqueous phaseof the emulsion.
 2. The adhesive emulsion of claim 1, the proportions byweight being about 3-15 parts of the coalescing agent and 2-15 parts ofthe plasticizing ester for 100 parts of said resin component.
 3. Theadhesive emulsion of claim 1, including an admixed thickener in theamount to raise the viscosity of the emulsion to about 10 - 100 poisesat 20* C.
 4. The adhesive emulsion of claim 1, including an admixedthickener selected from the group consisting of the water dispersiblealkyl and hydroxyalkyl celluloses, sodium salt of carboxymethylcellulose, polysaccharide gums, and polyoxyethylene of molecular weightwithin the range 4,000 to 4,000,000, the proportion of the thickenerbeing that giving to the emulsion a viscosity of about 10 -100 poises at20* C. when the proportion of water in the emulsion is approximately 40percent of the total weight thereof.
 5. In the emulsion of claim 4, saidthickener being hydroxyethyl cellulose.
 6. An adhesive emulsionconsisting essentially of the following components in proportion byweight approximately as follows: 70-110 parts of water, 100 parts of acopolymer of vinyl acetate and ethylene, the proportions by weight ofthe monomers copolymerized in 100 parts by weight of said copolymerbeing 75-95 parts vinyl acetate and correspondingly 5-25 parts ofethylene, 3-15 parts of the acetate of the monobutyl ether of ethyleneglycol, 2-15 parts of tributyrin, and 0.005-2 parts of hydroxyethylcellulose.
 7. The adhesive emulsion of claim 4, said thickener beingpolyoxyethylene of average molecular weight about 200,000.
 8. Theadhesive emulsion of claim 3, said thickener being guar gum.
 9. Theadhesive emulsion of claim 1, including an admixed organic liquiddiluent, the diluent being of evaporation rate above that of water andin the proportion of about 5-15 parts by weight for 100 parts of saidcopolymer.
 10. The adhesive emulsion of claim 1, wherein the resincomponent is ethylene-vinyl acetate, ethylene being present in an amountof from 10-18 parts by weight, the amount of vinyl acetate being thenecessary remainder to make 100 parts total weight of copolymer.
 11. Anadhesive emulsion comprising A. water, B. a resin component containingpolymerized therein i. an aliphatic l-olefin having from two to fivecarbons, ii. a vinyl ester of a lower monocarboxylic acid having fromone to seven carbons, and iii. a functionally reactive comonomer,selected from the group consisting of acrylic acid, methacrylic acid,itaconic acid, aconitic acid, maleic acid, fumaric acid, methacrylicacid dimer, the monoesters of maleic, fumaric and itaconic acids withC1- C4 alkanols, divinyl adipate, divinyl succinate, divinyl itaconate,diallyl fumarate, triallyl cyanurate, diallyl vinyl citrate, glycidylacrylate, glycidyl methacrylate, glycidyl vinyl ether, glycidyl allylether, N-methylolacrylamide, N-methylolmethacrylamide andN-ethylolacrylamide, the proportion of olefin in the resin componentbeing from 5-25 parts by weight, the proportion of functionally reactivecomonomer being from 3-10 parts by weight and the proportion of vinylester being the necessary remainder to make 100 parts total weight ofresin component, C. A water dispersible non-separating combination of i.a water-soluble coalescing agent selected from the esters of mono-C1-4alkyl ethers of C2-8 glycols with C2-4 saturated monocarboxylicaliphatic acids and ii. a plasticizing ester of glycerin with asaturated C2-4 monocarboxylic aliphatic acid, said coalescing agent andplasticizing ester being dispersed in substantially non-separatingcondition in the aqueous phase of the emulsion and being in weightproportion corresponding to about 3-15 parts of coalescing agent and2-15 parts of plasticizing esters for 100 parts of said resin component.